According to the first two paragraphs of this Wikipedia Page, leveling up boils down to a video game character gaining enough experience to unlock new skills or improve existing ones. I also like to think about leveling up as a player advancing to the next level (usually resulting in increased difficulty) in the game that they have been playing.
Do you see where this is going?
You can apply the logic of levelling up to your extracurriculars where you enhance an extracurricular that is already on your resume by adding to it or advancing the activity.
Pause.
This advice applies to rising seniors and juniors who have already been in established extracurricular activities for an extended period of time. If you are a rising freshman or sophomore, your priority should be finding extracurriculars to join or start. However, this is something that you will want to keep in mind down the road.
Play.
For students who already have an established list of extracurriculars, the best way to bolster your list is to enhance the extracurriculars that you already have. An enhancement can include starting a new initiative in your club, mentoring younger/newer students, or reaching new levels of achievement in the activity. These are only some strategies among the many ways you can level up an extracurricular.
So what are some examples of leveling up an extracurricular?
I inadvertently leveled up my extracurriculars in high school. I didn't consciously choose to find ways to advance my progression in the extracurricular, but naturally just wanted to get involved and stay involved, here are some of the things that I did:
Co-founded the first policy debate team in my Speech & Debate club (11th)
Created a new way of organizing my school's Science Olympiad roster (11th) (and taught classes to younger students but forgot about that and left it out of my app lol)
Consistently placed top 5 in the state in Science Olympiad (11th/12th)
Placed 1st in the nation (as a team) in online Quizbowl (fall of 12th)
(not related to HS apps, but in college I joined my collegiate eSports team which leveled up a hobby I already did in my free time)
Leveling up extracurriculars demonstrates commitment, dedication, initiative, creativity, expertise, leadership, and more. Leveling up is also really important so that your extracurriculars are not stagnant since you joined during your freshman year of high school. The continuous growth in your activity will help you get great LORs from your advisors and write awesome EC descriptions and essays.
So, how do you level up the extracurriculars you already have? Ask yourself:
What's something I have always wanted to do in this club that I haven't yet?
Ex. You host a massive fundraiser to donate to the target group that your club raises awareness about.
What are more advanced versions of the same activity I'm currently in? (joining the community-wide level of your organization instead of just your school's)
Ex. You write for your school newspaper and then apply to also write for your local newspaper.
Instead of stopping a project I already started for school or a club, can I turn it into a passion project?
Ex. You had a class coding project and decided to finish the code and add to it, kept working on it, and got it on a platform/accessible to a group of people so it can help others
What are other activities that I can translate a skill that I already have?
Ex. You're a treasurer of the school band and then ran for school treasurer or treasurer for a new club (this is best done junior year or before unless you translate the skill to a new job/internship/larger organization outside of school)
What's a hobby that I do that I could start to do in a more formal/organized way?
Ex. You do karate lessons for fun and then you start to compete on behalf of your karate gym
What's a hobby that I do that I could try to do at a more challenging level for myself? (because colleges still like to see hobbies so not everything needs to be through a formal organization)
Ex. You like to run for fun and then you decide to train for a half or full marathon.
I had a friend who loved knitting socks/scarves and then, senior year, knit an entire sweater. Writing an essay about leveling up their knitting skills in that way got them into an Ivy League school.
This is not an exhaustive list of how you can level up your extracurriculars. I would challenge you to brainstorm which of your extracurriculars you're motivated to get more involved in and start there to come up with ideas for how to take them to the next level.
Just like in a video game, leveling up an extracurricular will get you valuable experience points that you can write about in your essays and will allow you to be at a higher skill level than students in similar activities applying to the same schools.